General-Purpose Mail Filter

12.4 Daemon Mode

To start mtasim in daemon mode, use the
--daemon (or -bd) command line option. This mode
is not quite the same as Sendmail -bd mode. When started in
daemon mode, mtasim selects the first available
TCP port to use from the range ‘1024 -- 65535’.
It prints the selected port number on the standard output and
starts listening on it. When a connection comes, it serves a
singleSMTP session and exits immediately when it is
ended.

This mode is designed for use in shell scripts and automated test
cases.